This invention relates to a method of controlling a gas adsorption apparatus and more particularly to a method of controlling a gas adsorption apparatus of the kind including at least two sieve beds each containing molecular sieve bed material, each bed being cyclically operable in a charge mode to adsorb non-product gas from an air supply thereby to increase the concentration of a product gas in a product gas supply which passes to a product gas line, and in a vent mode to desorb the adsorbed non-product gas which passes to a non-product gas line, the beds being operated so at least for some of the time when each of the beds is operating in charge mode, the other or another of the beds is operating in vent mode.
Such apparatus typically are utilized for providing a product gas supply with an increased concentration of oxygen, for breathing in an aircraft, at high altitudes.
A potential problem with such apparatus is that the molecular sieve bed material can be contaminated with contaminants such as water, which is particularly present in air which is supplied to the apparatus at altitudes below say, 15,000 feet. At altitudes above 15,000 feet, the air supply tends to be drier and thus presents less potential problems to the operation of the gas adsorption apparatus. Although free water can relatively easily be removed from the air supply, some entrained water vapor can remain.